Urban-Wildland Fires: On the Ignition of Fuel Beds by Firebrands
Urban-Wildland Fires: On the Ignition of Fuel Beds by Firebrands
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发表时间：
2005-09
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通讯作者：
S. Manzello;Thomas G. Cleary;John R. Shields;Jiann C. Yang
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作者：
S. Manzello;Thomas G. Cleary;John R. Shields;Jiann C. Yang
几个世纪以来，城市野火一直困扰着美国。最近的城市野火包括2002年海曼大火，2000年洛斯阿拉莫斯大火和1991年奥克兰山火。城市荒地界面的火灾可能对人类生命、财产损失和当地经济产生破坏性影响。在城市荒地火灾中，树木和其他物体燃烧时会产生余烬或火把。这些火种被夹带在大气中，并可能被风带到很长的距离。热的火把最终会停下来，并可能点燃远离火焰的燃料，导致火灾蔓延。这个过程通常被称为斑点。了解这些热的火把如何点燃周围的燃料是减轻社区火灾蔓延的重要考虑因素。城市-荒地火灾研究的一个主要进展是开发了一个模型来预测由于燃烧物的影响而引起的材料的可燃性[2]。缺乏关于火把点燃远程物体能力的详细理论限制了可用于预测火把引起的火灾蔓延的详细计算流体动力学模型（CFD）的实用性[2]。详细的实验点火研究燃料床通常发现在城市荒地接口由于燃烧的影响，需要验证这样的模型。为此，建立了一套实验装置，研究了燃料床在燃烧火焰冲击下的着火过程。该装置允许燃烧剂在目标燃料床上的点燃和沉积。所用燃料床的含水量是不同的，所考虑的燃料是松针床和碎纸床。松针床是用来模拟充满松针的排水沟。碎纸床被用作典型的纤维素燃料的替代品，这些燃料将在阁楼空间中找到。通过将木材（美国黄松）加工成均匀几何形状的小圆盘来模拟燃烧物。在火灾模拟器/探测器评价器（FE/DE）上安装了燃烧器点火装置，以研究空气流动对燃料床着火倾向的影响。本研究的结果。
Urban-wildland fires have plagued the United States for centuries. Recent urban-wildland fires include the 2002 Hayman Fire, the 2000 Los Alamos Fire, and the 1991 Oakland Hills Fire [1]. Fires in the urban wildland interface can have a devastating effect on human life, property loss, and local economies. Embers or firebrands are produced as trees and other objects burn in urban-wildland fires. These firebrands are entrained in the atmosphere and may be carried by winds over long distances. Hot firebrands ultimately come to rest and may ignite fuels far removed from the fire, resulting in fire spread. This process is commonly referred to as spotting. Understanding how these hot firebrands can ignite surrounding fuels is an important consideration in mitigating fire spread in communities. A major advance in urban-wildland fire research would be the development of a model to predict the ignitability of materials due to firebrand impact [2]. The lack of a detailed theory on the ability of firebrands to ignite remote objects limits the utility of detailed computational fluid dynamic models (CFD) that could be used to predict fire spread by firebrands [2]. Detailed experimental ignition studies of fuel beds typically found in the urban-wildland interface due to firebrand impact are required to validate such models. Consequently, an experimental apparatus has been built to investigate the ignition of fuel beds as a result of impact with burning firebrands. The apparatus allowed for the ignition and deposition of firebrands onto the target fuel bed. The moisture content of the fuel beds used was varied and the fuels considered were pine needle beds and shredded paper beds. Pine needle beds were intended to simulate gutters filled with pine needles. Shredded paper beds were used as a surrogate for typical cellulosic fuels that would be found in attic spaces. Firebrands were simulated by machining wood (pinus ponderosa) into small disks of uniform geometry. The firebrand ignition apparatus was installed into the Fire Emulator/Detector Evaluator (FE/DE) to investigate the influence of an air flow on the ignition propensity of fuel beds. Results of this study are presented.